About this world
K2-125 b is a sub-Neptune orbiting K2-125, a cool red dwarf 405 light-years from Earth. It is about 2.2 times the size of Earth. It completes an orbit every 21.8 days at 0.12 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 321 K (48 °C): too cold for liquid water on its surface. By the "cosmic shoreline", it has likely held on to an atmosphere.
It was discovered in 2017 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction.